Currently there are no viable methods for separation of gold and other metals that are under 150 microns particle size from especially clay rich gangue material. A significant majority of the gold on the earth falls into this category, but most mining operations make no attempt whatsoever to recover gold in that particle size range. However, when the gold level is high enough, there have been efforts made to use sulfurous acid, cyanide or mercury based leaching processes to remove gold from the gangue material. These processes carry with them a number of significant environmental risks.
U.S. Pat. No. 7,293,568 and published U.S. Patent Application 2008-0178908, each of which is herein incorporated by reference in their entirety, teach methods of making stable, aqueous solutions of silicon. It has been unexpectedly discovered that aqueous solutions of silicon are useful in methods of extracting precious metals from clays and other gangue materials. These silicon chemical solutions are environmentally benign and enable the separation of fine gold and other precious metals from clay-rich gangue material by altering the ionic bonds between the clay and metal thereby allowing the use of industry standard vibration tables, concentrators, wash towers, hydro-cyclones and centrifuges and the like for separation and extraction of the precious metals from the gangue material.